This invention relates to a visible-light semiconductor laser and more particularly to a semiconductor laser having a wide lasing-wavelength range.
Some visible-light semiconductor lasers emit red light (.lambda.&gt;600 nm) at room temperature using an active layer of In.sub.0.5 (Ga.sub.1-x Al.sub.x).sub.0.5 P and cladding layers of In.sub.0.5 (Ga.sub.1-y Al.sub.y).sub.0.5 P (y&gt;x) in lattice-match with a GaAs substrate (see, Suzuki, Papers at the Meeting for publication of the Results of Research and Developments on Applied Optical Measurement and Control System, OAR-R-No. 6 p. 175).
Examples of the strained-layer-superlattice applied to lasers are GaAs/GaP.sub.x As.sub.1-x system and GaAs/In.sub.1-x Ga.sub.x As system, although they emit not visible but infra-red light (see M. J. Ludowise et al., Appl. Phys. Lett. 42 (1983) pp 257-259 and pp 487-489).